1. Field of the Invention
The invention relates to a device for protecting objects such as buildings, storage tanks, mooring docks and the like from damage that may occur from rising water, as in floods. The invention also includes key components of said device that act to protect said objects from flood damage by raising those objects above the level of the water.
2. Background Art
Every year, damage caused by flooding amounts to billions of dollars. Mankind has attempted to control floodwaters through such means as dams, levees, floodwalls, impoundment reservoirs, and the like. The cost of such means generally limits the application thereof to densely populated regions, where many people can benefit therefrom. However, when floodwaters rise beyond the capabilities of such means, or when floodwaters rise in areas not protected by such means, it is usually necessary to resort to temporary levees constructed by sandbagging, or else to admit defeat and allow the floodwaters to rise. As the floodwaters rise, objects such as buildings, storage tanks, mooring docks, and the like, in the path of the rising water may be damaged thereby, similarly, anything inside such buildings may also be damaged by the floodwaters.
It is easy to suggest that flood damage could be prevented by not constructing any object that may be damaged by floodwaters on land that is subject to flooding. However, there are two reasons why this approach is generally impractical. First, it is difficult to define which areas near a waterway are subject to flooding. Suppose one has access to historical records; one could define a flood plain as the land that was covered by the highest flood ever recorded, or as the highest flood recorded in the last 100 years, or by some other criterion. Just as surely as historical records are used to define a flood plain, some subsequent flood may exceed the historical standard. Second, land within the flood plain frequently has very high value, for several reasons. As rivers, estuaries and the like are frequently utilized for transportation by boat, the term being used herein to include ships and barges, it is necessary to construct facilities for loading and unloading cargo from such boats. Such facilities are necessarily situated adjacent to waters that are navigable in normal conditions, i.e., other than flood conditions. Flood plains also provide convenient locations for other means of transportation, notably railroads and highways. It is generally less expensive to build and operate such means of transportation along a river than overland. Many industrial processes require large quantities of water, and industries utilizing these processes must be located near an appropriate source of water. In electric power generation, for example, efficiency is enhanced by the use of cooling water. Paper is made by suspending cellulose fibers in water, and then pouring the suspension through a screen to create a felt-like substance, and squeezing the water out of that felt-like substance to create a sheet of paper. In addition, it is desirable to build residential and commercial buildings in locations near transportation facilities and manufacturing plants, so that flood plains become attractive locations therefor. It is also easier and less expensive to construct such buildings of flat terrain, such as a flood plain, than on adjacent sloping terrain. On a global scale, the amount of land deemed commercially useful is small enough that excluding flood plains therefrom would be unacceptable. In some regions, such as parts of China, land is so scarce that people build houses on wood pilings driven into the bottoms of waterways, or they live on boats. With the increasing population of the world, it is likely that mankind will continue to build on flood plains.
A logical extension beyond building a structure on a boat is constructing a floating structure that is constrained to a particular location. Such a structure typically remains at the same level relative to the surface of the water, even though the water may rise far above its normal level. Access to dry land is achieved through a rolling or swinging gangplank. Otis (U.S. Pat. No. 3,166,037) has described one such structure, though the objects of his invention relate primarily to the design and methods of construction thereof. Such structures are commonly constrained to a particular location by cables attached at one end to the floating structure and at the other end to anchoring devices built into the banks of the waterway. Alternatively, vertical posts driven into the bottom of the waterway may be used to constrain movement of the floating structure. As structures of this type float on the water at all times, they arc sensitive to waves and other local perturbations in the surface of the water. As a result, the structure may rock to and fro, and its structural members may also be subjected to considerable stress as one portion thereof may be raised more than other portions.
Floating structures for purposes other than residential and commercial buildings, and boat moorings, have been described. As an extreme example, Tellington (U.S. Pat. Nos. 5,398,635, 5,588,387 and 5,799,603) has described a floating airport. He has described means for maintaining the floating airport in its intended location by continually maneuvering it to head into the wind at the intended location. He has also described means for absorbing much of the motion of the waves, so that the floating airport can be kept flat and level, in spite of the waves. Grip et al (U.S. Pat. No. 5,131,109) have described a pontoon bridge that is tethered to the bottom of the waterway, with sufficient downward force applied through the tethers to keep the pontoons more nearly submerged that the normal buoyancy thereof would dictate. This approach reduces the likelihood that their bridge would rock to and fro as a result of waves on the surface of the water, and it also minimizes rocking of the bridge due to movement of vehicles on the bridge. Each of the structures described in the patents cited above floats all the time, supported by the water. As a result, there must always be some provision for connecting the floating structure to dry land, such as a gangplank or a service boat, and some provision for connecting the floating structure to land-based utilities, such as electricity, drinking water, fuel for heating, and the like.
A structure built on stilts, such as that described above, creates access problems for the user thereof. If such a structure is attached to pilings embedded in the bottom of the waterway, access is gained through boats or bridges. Such a structure offers no protection against rising and falling of the water level. In some parts of the United States, notably on the Outer Banks of North Carolina, houses are built on pilings embedded in the sand near the waterfront. The objective of such construction is to allow the high waves associated with stormy weather to sweep over the beach, but beneath the living area of the house. As the waves cannot smash into the living area of the house, damage thereto is avoided. The same construction has been applied to construction on the flood plain adjacent to a river, for the same reason. However, in either case, access to the living area can be gained only by means such as stairs, ramps, elevators and the like. With respect to structures built on stilts, several issues must be addressed. If the structure is to be built on pilings in the bottom of the waterway, is the utilization of the airspace over the surface of the water for structures economically feasible, given the higher cost of construction and access problems associated therewith? Is the protection against variations in water level sufficient? If the structure is to be built on pilings embedded in the earth near a waterway, does the reduced risk of damage from floodwater justify the increased construction cost and inconvenience of access?
In U.S. Pat. No. 5,347,949, Winston has described what he calls a floating, or floatable, house. The latter term is more descriptive, because the house rests on a land-based foundation, except during times of high water. Then it floats on pontoons made of foam polymeric material, and on air bladders adjacent thereto. Telescoping piers serve to constrain the floating house to a specified location. Winston's stricture becomes a floating structure, subject to the limitations and inconveniences discussed above, when the water level rises sufficiently.
There is another class of devices, floating dry docks, that is only remotely germane to the present field of art. These are devices that can be at least partially submerged to place a boat therein, and then floated to raise a boat out of the water for maintenance. Furst (U.S. Pat. No. 4,381,723) describes one such device that is tethered to the bottom of a waterway by a parallelogram linkage. It may be construed as analogous to Winston's house, to the extent that expelling water from buoyancy chambers therein provides means for keeping the upper surface of the drydock above a varying water level. However, the concept of partially submerging a drydock to place a boat therein is not related to the problem addressed by the present invention, namely, to keep an object above the water in spite of rising water level.
It is believed that the flood protection device, as set forth herein, is neither taught nor rendered obvious by the prior art cited above.